Tim Vickery Aug 26, 2026, 10:03 AM ET It was set up to be one of the transfer sagas of the summer: would Vinícius Júnior be seduced by the idea of leading Arsenal's challenge to win the UEFA Champions League for the first time? In the end, of course, he was not, and, with a renewed contract, he goes into the current season more a Real Madrid player than ever. His compatriot and teammate Rodrygo, it seems, was presented with the same dilemma a year ago. Speculation linked him with Arsenal, but the lesson of the story seems to be that the glamor machine remains intact. If Real Madrid wants to keep you, then you do not choose to leave. And, at the start of a career, if Real Madrid come knocking, you do not refuse. But in this case, perhaps the rule should not apply with such rigidity. It is one thing to be an established star with Real Madrid and it is another entirely to be a young South American, taking first steps in Europe and striving to find space in a dressing room packed with stars.

The latest to serve as a cautionary tale is Argentine playmaker Franco Mastantuono, who joined Madrid from River Plate a year ago. The left-footed attacking midfielder managed to feature in a total of 35 first-team matches last season -- no mean feat for an 18-year-old -- but he started just 17 of those. But the figure of one solitary assist and just six starts after November is disappointing for his talent. He scored three goals, shared between La Liga, the Copa del Rey and the Champions League, where he became the youngest player in the club's history to appear in the competition. Now, he has joined Italian club Fiorentina on loan this season.

None of this should cause the slightest surprise. True, Mastantuono crossed the Atlantic as an important and established first-team player with River Plate. But the standard of the contemporary Argentine league is not high -- none of their teams have won the Copa Libertadores since River did it in 2018. The step up in quality and intensity of the game were bound to be a challenge, and Mastantuono is not a player blessed with extreme pace. He is probably not quick enough to shine wide on the right, in the position where Madrid often used him. A more subtle player, his game may develop in-field, controlling possession and using his excellent left foot to distribute passes. These are crafts that take time to learn, and, only just turned 19, Mastantuono has plenty of time ahead to develop.

But now there is a problem of momentum -- a key concept in a career as short as that of a professional player. He has gone to Real Madrid, been weighed and, temporarily, found wanting. Will that turn into something more permanent? How damaging is the perception of not having lived up to expectations at Real Madrid? How much has it undermined his own self-belief? He has lost the momentum that carried him across the Atlantic as a wonderkid, and momentum can be a difficult horse to recapture. Six years ago, the next 18-year-old South American attacking midfielder off the rank was Reinier, captain of Brazil's Under-17 team and getting some game time in the all-conquering Flamengo of Jorge Jesus. Real Madrid signed him -- but he never even played a single competitive game in their colors. He was loaned to Borussia Dortmund in Germany, to Girona in Spain, Frosinone in Italy, and then back to Spain to Granada before Real gave up and he went back to Brazil, where so far he has done little of note with Atlético Mineiro. Still only 24, Reinier has yet to recapture any of the momentum that was behind him when he joined Real Madrid. Hindsight is always 20-20, but in retrospect it would surely have been better to do the unthinkable -- to say no to Real Madrid, stay a while longer in Brazil and then build his European career step by step.